Making Noise about Underwater Acoustics

The IWC and the U.S. Marine Mammal Commission review underwater noise pollution

The Humane Society of the United States

By Naomi Rose

For the past decade, The HSUS has worked to protect marine mammals and other marine wildlife from a growing cacophony of noise in the ocean environment. It isn't that the oceans were ever a silent place; there are many natural loud sounds in the sea, produced by storms, earthquakes, and other sources, but human technology has upped the ante considerably. Global shipping, military sonar, explosions, oil and gas seismic exploration, and other activities have increased the level of noise in the ocean significantly since the turn of the last century, a phenomenon whose effects are only recently becoming better understood.

Sound, unlike light, travels very well in water, far better than in air, and many species of marine wildlife have evolved to take advantage of this characteristic. The most familiar example to most people is the echolocating dolphin—dolphins have a natural ability to use sonar. A dolphin produces loud clicks that bounce off objects and return echoes to a brain uniquely able to interpret them. With echolocation alone, bottlenose dolphins can tell a dime from a quarter, wood from metal, and can even distinguish what is inside certain containers.

Less familiar to the general public is the long-range communication abilities of baleen whales (whales, such as the gray and blue, who have sieve-like plates instead of teeth hanging from the top of their mouths) who produce loud low-frequency calls that are capable of traveling tens, if not hundreds, of kilometers underwater.

The noisier the marine environment becomes, the more difficult it will be for marine mammals to navigate, forage, communicate, and otherwise function in their habitat. In fact, some human-caused sounds can injure and even kill marine mammals.

Turning up the volume

Although concerns about adverse impacts from human-caused (or anthropogenic) noise have been around for many years, only in the 1990s did attention focus sharply on this threat to marine life. The main reason was the development of new research and military technologies that use sound to accomplish their tasks. The Acoustic Thermometry of Ocean Climate project, which used loud low frequency sound to study global warming (sound travels faster in warmer water), and Surveillance Towed Array Sensor System Low Frequency Active sonar came to light in 1994–5 and galvanized environmental organizations and the public to fight the proliferation of noise-producing technology.

The HSUS, along with groups such as the Natural Resources Defense Council and Cetacean Society International, was a leader in the fight against Low Frequency Active Sonar, but our efforts led us to realize that other sound sources, notably mid-frequency active sonars and seismic airguns used in oil and gas exploration and research, were possibly more hazardous to marine mammals—and these were not new technologies like LFA. Mid-frequency sonars and airguns have been in use for decades and have quite probably been harming marine mammals, unseen and unstudied, for all of that time.

Suspicious strandings

The defining event that spotlighted mid-frequency active sonar as a threat to marine mammals took place in March 2000. A mass stranding of beaked whales (one dolphin also died, but apparently of unrelated causes) occurred around the Bahamas after a U.S. Navy exercise in which mid-frequency sonars were used. Entirely coincidentally, trained marine biologists were on hand to witness and deal with the strandings. Some whales were refloated, but several died, and necropsies (animal autopsies) were conducted.

The subsequent investigation, the most thorough to date of such an event, was done with the cooperation of the Navy; the conclusion was that sonar was the cause of the injuries observed, although how the sound caused the injuries was not clear. This led to a reexamination of numerous other mass strandings, a significant number of which had been reported by scientists, as early as 1991, to be associated with naval exercises.

These navy-linked mass strandings of beaked whales and other species are occurring in the Canary Islands, Japan, and elsewhere, with either mid-frequency sonar or live-fire exercises known to be in use nearby. The most recent suspicious strandings occurred in the summer of 2004—early in July, approximately 150 melon-headed whales (actually a large dolphin species) live-stranded in Kauai, Hawaii, near U.S. and Japanese Navy ships using mid-frequency sonar, while two beaked whales stranded dead in the Canary Islands in association with NATO exercises in late July. Several bottlenose dolphins, as well as a pygmy sperm whale, stranded in North Carolina the week of August 6–7, with Navy activity reported offshore (the details of this incident are still unclear). Two beaked whale strandings, in 2000 and 2002, were associated with the use of seismic airguns.

A growing body of scientific evidence and scrutiny strongly points to noise as the culprit in these strandings—with beaked whales especially vulnerable, perhaps, but other species (for example, minke whales, pygmy sperm whales, and even bottlenose dolphins) at risk as well.

The advisory committee on acoustic impacts on marine mammals

As a result of the growing public interest and concern with the impacts of military and other anthropogenic noise sources on marine mammals, the U.S. Congress and the International Whaling Commission independently decided to examine the issue more closely. In December 2003, the U.S. Marine Mammal Commission, at Congress' order, convened an Advisory Committee on Acoustic Impacts on Marine Mammals, consisting of 28 experts and stakeholders, including the U.S. Navy, oil and gas and shipping company representatives, researchers, government agency officials, and environmental and animal protection organizations (including The HSUS). This committee is charged with providing advice and recommendations to the MMC (and the MMC will subsequently report to Congress) on how best to manage anthropogenic noise and its impacts on marine mammals. The Committee held a series of three-day public meetings, in February, April, and July 2004, and a three-day international workshop on marine noise management and mitigation in London in late September. This workshop brought an international perspective to what is clearly a global issue and resulted in some concrete suggestions for how noise might be reduced and mitigated using both national and international legal instruments already available to governments.

There will be two more meetings at a minimum, in November 2004 and February 2005. In addition, the MMC is sponsoring or co-sponsoring related meetings and workshops on specific sub-topics of the noise issue, including shipping noise and beaked whale biology.

The HSUS is sending representatives to most of these related meetings. On the committee, we seek to ensure that its advice and recommendations emphasize the Precautionary Principle (which instructs that when "there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used" as an excuse to prevent that damage), the growing body of scientific evidence implicating noise in both lethal and sub-lethal impacts, and animal welfare as well as population level concerns.

The International Whaling Commission

The IWC Scientific Committee met in June and July 2004 in Sorrento, Italy, and held a special-topic symposium on noise during the sessions of its environmental concerns standing working group (called the E group). The symposium pulled together several experts on noise and its impacts on marine mammals and discussed the implications of new research, particularly on beaked whales (a topic also examined in detail by the MMC-sponsored beaked whale workshop held in April 2004—see above). The symposium received the input of as many as 100 international experts in cetacean biology, as well as several acoustics experts, and in its report "unanimously agreed that there was now compelling evidence implicating anthropogenic sound as a potential threat to marine mammals."

The E group also stated that "[it] recognizes the important role of science in helping to explain why whales respond behaviorally to or are injured by various sources of man-made sound. However, [it] also recognizes and wishes to emphasize that measures to protect species and their habitats cannot always wait for ultimate certainty levels of scientific confirmation. In such cases it is appropriate to adopt the precautionary principle."

In for the long haul

With man-made noise in the ocean only likely to increase—as shipping traffic expands, active sonar (such as LFA) proliferates, and oil and gas exploration activities become more important to a fossil-fuel driven economy—we can only hope that the attention now being focused on this issue will bear fruit before much more damage is done. However, noise-producing groups such as the Navy and the oil industry are highly resistant to regulation and oversight and have already ignored or dismissed evidence that their activities are harming marine mammals around the globe.

Knowing that we cannot expect bodies such as the MMC and the IWC to work without support, we at The HSUS will continue our efforts worldwide to maximize protection for marine mammals and their ecosystems from the onslaught of noise pollution. We will also call on our constituents for assistance via action alerts when necessary.